This invention relates to electromagnetic interference and heatsinks.
Heat sinks act like radiation antennas, which can generate electromagnetic radiation levels that exceed U.S. and European regulations.
A large heatsink that is close to a high frequency microprocessor may behave as an antenna of electromagnetic radiation induced by the microprocessor. The emitted electromagnetic radiation can affect the performance of nearby devices.
In a first aspect, the invention provides an apparatus including a semiconductor device and a heatsink thermally coupled to the semiconductor device. The heatsink is located and formed to screen the device from external electromagnetic radiation or to contain radiation produced by the device.
In a second aspect, the invention provides an apparatus including a semiconductor device, a heatsink thermally coupled to the semiconductor device, and a grounding structure. The grounding structure has a capacitive coupling to the heatsink.